Container base



FIG. 1 is a top, right side perspective view of a container base, showing our new design;

FIG. 2 is a bottom, left side perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side elevational view thereof;

FIG. 6 is a left side elevational view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is a bottom plan view thereof.

The broken lines in the drawings depict portions of the container base that form no part of the claimed design. 

CLAIM The ornamental design for a container base, as shown and described. 